It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

creating a 3D rectangle in Java without using any 3D libraries like Java3D or OpenGL but why?
–
Pradeep SimhaDec 28 '12 at 16:24

You are going to have to explain a little more a 3D rectangle is just 6 points in space.
–
FrozendragonDec 28 '12 at 16:24

1

Are you asking for how to write a renderer? There are plenty of sources for that... most in C++ but it would not be hard to translate... Or maybe you are asking for a software render library -- I doubt that exists/ has significant support since it doesn't make sense to do in many contexts
–
gbtimmonDec 28 '12 at 16:26

It's creating that render method that takes some calculation. And that calculation would be different for every 3D shape you want to define.

Your calling routine would have to figure out the order in which to render all of your 3D shapes. basically, the furthest 3D shapes have to be rendered first, so that the closer 3D shapes overlap properly.

A 3D library not only has all of this figured out, it is also optimized so that a 3D scene can be rendered in the shortest amout of time possible.